Triad arrangement of normal SE lymphatic, vein, and artery. a). CD31 immunohistochemical purple staining of lymphatic (L) vein (V) and artery (a), with Methyl Green nuclear counterstaining. b). 10.1.1 immunohistochemical staining identifies the SE lymphatic vessel. The nonspecific staining in the upper right corner is myoglobin pseudoperoxidase-positive muscle. c). Intravenously injected FITC L. lycopersicum lectin labels the artery and vein, demonstrating that they are functional in circulating blood. d). Texas Red Dextran injected subcutaneously into the tail base labels the lymphatic vessel, indicating that it is functional in circulating lymph. Scale bar 50 μm.